From acf63cc2308da8708a0bc23877806fa19dac3ad2 Mon Sep 17 00:00:00 2001
From: Jake Zerrer <him@jakezerrer.com>
Date: Mon, 1 Dec 2025 15:16:25 -0500
Subject: Add parallel composition

---
 src/unheard/cycles.clj | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/unheard/cycles.clj b/src/unheard/cycles.clj
index 513b090..5511d64 100644
--- a/src/unheard/cycles.clj
+++ b/src/unheard/cycles.clj
@@ -29,6 +29,20 @@
   [& args]
   {:v (vec args) :type :f})
 
+(defn p
+  "Parallel combinator: all children occur simultaneously.
+
+  Each child gets the full time duration of the parent.
+  All children are active at the same time, producing overlapping intervals.
+
+  Equivalent to TidalCycles/Strudel 'stack' operator.
+
+  Example:
+    (p :a :b :c) with cycle-length 1
+    => [[0 1 :a] [0 1 :b] [0 1 :c]]"
+  [& args]
+  {:v (vec args) :type :p})
+
 (defn scalar? [x]
   (not (and (map? x) (:type x))))
 
@@ -48,6 +62,10 @@
       (* n (reduce lcm 1 (map compute-cycle children))))
 
     (= :l (:type node))
+    (let [children (:v node)]
+      (reduce lcm 1 (map compute-cycle children)))
+
+    (= :p (:type node))
     (let [children (:v node)]
       (reduce lcm 1 (map compute-cycle children)))))
 
@@ -72,7 +90,13 @@
       (let [children (:v node)
             n (count children)
             child-idx (mod iteration n)]
-        (unfold-node (nth children child-idx) start end (quot iteration n))))))
+        (unfold-node (nth children child-idx) start end (quot iteration n)))
+
+      (= :p (:type node))
+      (let [children (:v node)]
+        (mapcat (fn [child]
+                  (unfold-node child start end iteration))
+                children)))))
 
 (defn unfold
   "Unfolds a pattern tree into concrete time intervals.
-- 
cgit v1.2.3